Iced coffee has risen in popularity over the last decade. Iced coffee is standard hot brewed coffee that is chilled or served over ice.
An alternative to iced coffee is cold brew coffee. As compared to standard hot brewed coffee, cold brew coffee has a delicate flavor profile that is less acidic than hot brewed coffee. For this reason, some prefer cold brew coffee over hot brew coffee.
Recently, nitrogen infused cold brew coffee products have become popular, especially in single use cans. Nitro cold brew (NCB) coffee is an emergent food trend for ground, roasted coffee beans filtered slowly (steeped) through a cold, room temperature, or hot-bloom water brewing process for 8 or more hours (upper range ˜36 hours). The beverage is stored anaerobically in cans or stainless steel kegs, and charged with nitrogen gas. The nitrogen gas infusion may be similar to the nitrogen widgets used for canned Guinness beer, and imparts small bubbles to the beverage which do not easily dissolve in water. This results in a creamy frothy head, imparting sweetness, less acidic taste and giving a fuller, thicker mouth feeling to NCB beverages when compared to regular coffee brews. Since the single use can product is relatively new, food safety requirements have been evolving. Recently, it has been discovered that growth of certain bacterium can be a problem in these products. Particularly, Clostridium botulinum (C. bot) has become a concern to both producers and regulators.
The Food and Drug Administration (FDA) has become concerned with C. bot in cold brew coffee products. Current FDA guidelines on the prevention of C. bot in chilled products provide for several ways to inhibit growth. These processing guidelines for products with more than 10 day shelf life include: a heat treatment of 90° C. for 10 minutes or equivalent lethality at the slowest heating point in the food; a pH of 5.0 or less throughout the food and throughout all components of complex foods; a minimum salt level of 3.5% in the aqueous phase throughout the food and throughout all components of complex foods; a water activity (aw) of 0.97 or less throughout the food and throughout all components of complex foods; a combination of heat and preservative factors which can be shown consistently to prevent growth and toxin production by non-proteolytic C. botulinum. 
Thus, the existing guidelines that can be applied to a beverage include adding salt to a 3.5% salinity, producing a more acidic product (pH below 5.0), and heating the product in the packaging to 90° C. or higher for 10 minutes.
All of the foregoing, although capable of inhibiting C. bot growth in cold brew nitro coffee, have the downside of altering the flavor profile of the product, which may result in an unsatisfactory taste to the consumer.
For example, heat can leave the cold brew coffee with a bitter and yeasty taste and a nitrogen dosed can has pressure limitations to the can due to the existing positive pressure already in that can at chilled temperatures. Salt is not an option as it would alter the flavor and, while it may be possible to increase the acidity, this has the downside of departing from the flavor profile that makes nitrogen infused cold brew coffee a popular product. Cold brew coffee typically has a pH range of 5.5-6.5 and since the pH scale is logarithmic, a significant amount of acid would need to be added to get the beverage below pH 5.0.
US 2017/0231245 discloses a ready-to-drink cold brew coffee product with a shelf life up to one year without refrigeration before consumption. However, the method of preparation involves heating a cold brewed mixture to a temperature of less than 100° C. for less than 1 minute to thereby form a pre-fill coffee composition. After heating, the method includes pouring and increasing a temperature of the pre-fill coffee composition to at least 82.2° C. and holding the coffee composition at the temperature of at least 82.2° C. for at least 30 seconds to form a filled coffee composition. As mentioned, this has the potential to affect the flavor profile of the cold brew. Moreover, the method does not address nitrogen dosing of the coffee.
The nitro coffee industry has generally believed that the addition of the nitrogen is not only important to provide for the gentle bubbled profile of the beverage but to also displace oxygen to inhibit growth of bacteria—particularly aerobic bacteria. Thus, the industry has generally tried to avoid oxygen within the canned coffee product. Oxygen also has another downside in that its presence generally limits shelf life in that the food processing industry often tries to remove oxygen in order to prolong shelf life.
Thus, both the food industry and the more niche nitro brew industry has sought to avoid oxygen. However, this lack of oxygen actually encourages C. bot growth as the bacterium thrives in an anaerobic environment.
Therefore, there exists a need for a cold brew coffee product and processing method and system that inhibits C. bot growth while preserving the flavor profile and at the same time providing for suitable shelf life.
There further exists a need for methods of manufacturing nitro coffee products, whether cold brewed, hot brewed, or iced, that inhibit C. bot growth and provide for suitable shelf life of the packaged product.